Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the wellbore fluids from the subterranean reservoir to a storage facility on the surface.
Wellbore fluids often contain liquids, gases and entrained solid particles. Because most downhole pumping equipment is designed to primarily recover liquid-phase fluids, excess amounts of gas or solids in the wellbore fluid can present problems for downhole equipment. For example, the centrifugal forces exerted by downhole turbomachinery tend to separate gas from liquid, thereby increasing the chances of cavitation or vapor lock. Large slugs or pockets of gas passing through the pumping equipment exacerbate this problem.
Solid particles entrained within the wellbore fluids create similar problems. Solid particles may emanate from a number of sources, including rust, scale and geologic matter. Larger solid particles moving through the pumping system may create blockages or abrade sensitive seals or bearings, or otherwise impair the performance of downhole machinery. To reduce the presence of solid particles in the pumping system, prior art pump assemblies have been fitted with screens or filters. While generally effective at limiting the amount of solid matter passing through the pump assembly, the screens or filters quickly become clogged, thereby adversely affecting the performance of the pump assembly.
Despite these advances in technology, there is therefore a need for an improved downhole pumping system that is more resistant to the inefficiency and damage caused by solid particles and gas entrained in the wellbore fluid. It is to these and other deficiencies in the prior art that the present invention is directed.